linux-kernel - Re: [RFC][PATCH] objtool,x86_64: Replace recordmcount with objtool

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Message-ID: <CABCJKucn5o+PgMnKwHOGRnhTdVk9Dnd2QZwy54wXYwQYNUNjBw@mail.gmail.com>
Date:   Wed, 22 Jul 2020 11:07:13 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kbuild <linux-kbuild@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
        X86 ML <x86@...nel.org>, Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [RFC][PATCH] objtool,x86_64: Replace recordmcount with objtool

On Wed, Jul 22, 2020 at 10:58 AM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> On Mon, 20 Jul 2020 09:52:37 -0700
> Sami Tolvanen <samitolvanen@...gle.com> wrote:
>
> > > Does x86 have a way to differentiate between the two that record mcount
> > > can check?
> >
> > I'm not sure if looking at the relocation alone is sufficient on x86,
> > we might also have to decode the instruction, which is what objtool
> > does. Did you have any thoughts on Peter's patch, or my initial
> > suggestion, which adds a __nomcount attribute to affected functions?
>
> There's a lot of code in this thread. Can you give me the message-id of
> Peter's patch in question.

Sure, I was referring to the objtool patch in this message:

https://lore.kernel.org/lkml/20200625200235.GQ4781@hirez.programming.kicks-ass.net/

Sami